TPWD 1960 F-4-R-7 #564: Evaluation of Selective Shad Control Work at Fincastle Lake

Report of Fisheries Investigations Evaluation of Selective Shad Control.Work at Fincastle Lake by Leonard D. lamb Project Leader Dingell-Johnson Project F-h-R-T, Job E-T April 1, 1960 - October 31, 1960 H. D. Dodges - Executive Secretary Texas Game and Fish Commission Austin, TEXss Marion Tools Kanneth C. Jurgens & William H. Brown Coordinator Assistant Coordinators A.B S T R A.C T The total kill of the fish population in Fincastle Lake was undertaken as a means of evaluating the reSults of an at- tempted shad control on.May 20-21, 1958. This control was the result of survey work under Jabs B-17, Project F—h-R-h and 3-26, Project F-hwR-ESo Other survey work as well as the shed control attempt were reported under Job Ew6, Project F-h-R-S, Net checks revealed that before the selective treatment, gizzard shad comprised 6901 perCent of the catch, while following the selective kill shad were reduced to lo5 percent, The three shad taken during the check netting, that followed the treatment, were all large femaleso Each was gravid, but the physical condition of the eggs indicated that none of them would spawn during the summer or fall of 19580 There is no indication that any shad spawn occured until June 1959 when the good fishing, that had prevailed since the selective treatment, ended, This condition appeared to coincide with the appearance of schools of small shed in the lake and poor fiShing became the rule. A not check in January 1960 revealed that shed made up #6 percent of the nettable populationo This was raised to 55,25 percent by the not check made in April 1960. The return of the gizzard shad to position of dominance in the population led to a total kill attempto This was done by the use of 2,5 percent synergized rotenone liquid applied at the rate of 0,50 partswperemillion in two applications at l8~hour interval. The application was made by gravity flow treatment drums in open water and pressure pump spray in vegetation along the shoreline. Attempts at estimating the number and weights of each species killed were not successful as vegetation, wind, and fish eating mammals, birds, and reptiles were presento These combined with people, who picked up many of the more desirable fish made reasonably accurate estimates almost impossibleo A.diligent search was made to locate and pick up all the shed whose size indicated that they might have escaped the selective kill of 1958o A total of five large shad were foundo They ranged in size from 2506 to 3,12 poundsa Each of the three females were gravid and the two males appeared to be in condition to spawn within 30 to 60 dayso The remainder of the gizzard shad population was divided into three size groupsa:v The larger size group ranged from 10 to 11 inches and appeared to be ready to spawn, The other groups were 8 to 10 and 5 to 7 inches respectivelyo It would appear that the 1959 gizzard shad production consisted of three separate spawns that covered the period from June to October or Novembero . Continued A B S T"R A C T That the rise and fall of the shad population has a marked effect on the growth of the game species is quite evident in the data presented in the tables. The average weight of game fish dropped when the shed population was drastically reduced, but rose sharply when the 1959 spawns became availableo The information gained from the work on Fincastle Lake indicates that the benefits from shad control work will not last more than.two years unless the entire shad population is removed. The removal of the entire shad population will require the sacrifice of a fairly large percentage of the game fish population, but the gain is believed to justify the costa Job Completion Report State of TEXAS Project Noe F-hme7 Name: Fisheries Investi ations and Serve s of the waters of Region E-B Job Noo E-T Title: Evaluation of Selective Shad Control _ Work at Fincastle Lake _ _l_a_ll_l__l_nl,_1_.__l__l__l_l.l__1ll_ Period Covered: April 12 1960 - OctOber 31: l960 OBJECTIVES To evaluate selective shad control work at Fincastle Lake by chemically killing the existing fish population to determine its species composition by numbers and weightso HISTORY Fincastle Lake is a privately owned lake on the headwaters of Catfish Creek in Henderson Ocunty, Texasfl This lake is located on the Trinity River watershed and is a slightly acid lakeo A.survey was made of this lake under Jobs BwlT, Project thmeh, and Bm26, Project thme60 Other surveys and experimental gizsard shad control work were accomplished and reported under can Em6, Project thme50 Net checks made during the Trinity River watershed survey showed Fincastle Lake to have a nettable fish population made up of 5lo6 percent giznard shade Net collections made prior to the selective shad kill in 1958 indicated the shed popue lotion to be 6901 percent of the net catcho Rough fish species composed 75ot percent of all fish nettedo An experimental attempt to control the shed population was made on May 20m2l§ 19580 This was accomplished by applying 205 percent synergised rotenone liquid by gravity flow drum at the rate of 0°065 partsmpermmillion followed after 18 hours with another application of the same concentrationo It was found that the split application provided a sustained toxicity which resulted in a good shad kill with little harm to game specieso The presence of a south wind caused the dead fish to drift to the north shore where they could be estimatedo The shad kill from this treatment was estimated at 36,960 fish weighing l6,592 poundsu Net checks subsequent to the selective kill produced only three shed in six net runs with 500 feet of gill not set overnighto These nets were the same mesh size as those used before the treatment and were set in the same locationso The three shad collected during the first year following the selective shad treatment were all large? adult femalesc The first was taken in June and one was taken in both July and Augusto These fish were gravid but gave no indication that Augusto There is evidence to support.the belief that no spawn of chad was Obtained in l958, but such was not the case in 19599 The fishing improved for both crappie and bass following the treatment and remained good until June l959o There were indications that a large spawn of shad occurred at this time and fishing became pooro The lack of fishing success cone tinned and in January 1960 a net check was madeo The results of this check showed the nettable population of the lake to consist of #6 percent shad while further net checks in April showed an increase in shad to 55025 percent of the catcho The shad netted during the 1960 survey were of two sizes and it was believed that they represented the 1959 spawn of a relatively few large shad who were able to survive the selective shad kill of 1958o Since there is a definite size differential between the shad that escaped the selective treatment in 1958 and their yearling offspring, it was believed that a total kill of the species present would reveal the approximate number of brood shad that remained in the lakeo PROCEDURE Fincastle Lake covers as acres and contains 382 acreefeet of water with a maximum depth of 15 feeto A total of 130 gallons of 205 percent emulsifiable _ rotenone liquid was applied to the lake in two applications of 0,50 partSmpermmillion each, separated by an l8whour intervalo The applications were made with gravity flow drums in the open lake and pressure pumpesprayer in the vegetation around the shore lines The first application was begun at 2200 p0 m. April 25, 1960, and the second was begun at 8:00 ao mo April 26, 19600 All_efforts to estimate the total numbers and weights of the various species killed were hampered by the people who picked up the more desirable fiSh as soon as the treatment was concludedo Many small shad were taken to be frozen for use as trotline baito The relative abundance of the various species was noted and is recorded on Table lo The data collected after this treatment has been compared with that previoushy collectedy both'before the selective kill and during the interval between the two treatmentso A very diligent search was made to recover all the large shad that were believed to have survived the selective killo These specimens formed the brood stock that were able to repopulate the lakeo RESULTS The treatment, as previously stated, was begun at 2200 p0 mo April 25, 19600 Two boats equipped with gravity flow treatment drums and one with a John Bean Not th pressure sprayer started operations simultaneouslyo The first fish were noted in distress within 30 minutesu These fish were shad but soon largemouth bass, sunfishes, crappie, bullheads, spotted suckers, channel catfish, and spotted gars were notedo Largemouth bass weighing as much as 7% pounds were taken before darko No bass was observed weighing less than 12 ounceso Treatment was resumed at 8:00 at mo, on April 26, with the procedure exactly as that followed the previous dayo Many species appeared after this application that were not noted on the first dayo Bowfins, grass pickerels, smallmouth'buffalo, and carp were the most important of this groupo A complete list of species identified from this lake is given in Table 1, together with symbols indicating the frequency of their appearance, A total of 2H species representing 16 genera and 10 families were observed, Specimens of two amphibians were observed among the dead fish and were inw cluded in the checklist, They were the western dwarf siren and the spotted salamander, Several species were observed among the fish killed that had not been taken in nets} A total of five smallmouth buffalo weighing from 22 to #5; pounds were noted, There were no small buffalo which was true of the carp where only two specimens were found, Bowfins and grass pickerels were known to be in the lake, but had never been taken by nets, Channel catfish were present, but rare and none had been netted, The warmouth was rather common among the dead fish, but rarely taken by nets, Green sunfish, orangespotted sunfish, and yellowbelly sunfish were much more numerous than the netting indicated, but_were so small that the nets were not likely to take them often, The large number of vultures, crows, racoons, skunks, turtles, and other fish eaters consumed many fish and further complicated the task of estimating the number and weight of the various species killed, The margin of the lake was heavily vegetated with shrubs and aquatic plants extending several yards from shore on all residence, Constantly changing winds prevented the formation of large drifts of fish and many trips around the entire lake were made to determine the results of the treatment, A total of 39 bass, whose weights were estimated at from 2 to 6 pounds, were counted and added to the 18 bass, weighing from 2 to 7% pounds, that were picked up on the first day of treatment, This made a total of 57 bass weighing 2 pounds or more, punctured by turtles and not floating, Fish continued to rise to the surface for four days following the last appliw cation of rotenone, which made the possibility of an accurate estimate of the kill rather remote, Many fish that floated on April 25 were badly decomposed and were broken up by wave action before April 29 or were eaten by birds, mammals, or turtles, A very careful check was made to determine the make up of the shed population, Many of the smaller shad were threadfin shad that could have come up stream from Pharris Lake which is less than five miles below Fincastle and on the same tributary to Catfish Creek, Pharris Lake was stocked with threadfin shad, shortly after the selective kill on Fincastle Lake in 1958, and a recent copper sulphate treatment revealed that the stocking was very successful, The bulk of the shed population was made up of giszard shad in four general size groups, The largest shad weighed 3,12 pounds followed by four others weighing 2,50, 2,19, 2,12, and 2,06 pounds respectively, The three larger specimens were females, This, when combined with the three specimens taken in nets following the first treatment, gives a total of 6 females and two males that survived the selective kill in 1958, It is believed that the 5 large shad formed the brood stock that failed to spawn in 1958, but produced three spawns in 1959, The smaller gizzard shad were in three general size groupso One group measured from 10 to 11 inches, total length, while the other two groups were from 8 to 10 and from 5 to 7 inches long, respectivelyo Whether each of these size groups represent the spawn of a single female or a partial spawn of more than one female is a question that cannot be answered, The smaller size group of gizzard shad and the threadfin shad were too small to be taken in the gill nets which have a ls-inch square mesh, There is little doubt that the gizzard shad population was well on the way to regain the dominance it had held before the control attempt in 1958, Each of the three large females was gravid and the condition of the eggs indicated that a spawn could be expected by early June, The 10 to 11 inch size group were also in breeding condition, with both males and females appearing to be less than 60 days from spawning. The effect of the selective kill on the mettable fish population in Fincastle Lake can be seen in Tables 2 and 3, Before the selective kill, the net catch was dominated by giazard shad to the extent that 69,1 percent of the number and 60,7 percent of the weight were this species, This is rather interesting when one considers that several species are present that attain a much larger size than do the shed, Following the shed control attempt, this species made up only 1,5 percent of the not catch by number and 209 percent by weight, Netting done just prior to the total kill showed that the shad had recovered to the extent that 50.6 percent of the number and 31,5 percent of the weight were of this specieso The smaller size of the individual shad may be attributed to the fact that none of them appeared to be more than one year of age, Another interesting observation may be made when the data, in Tables 2 and 3, are examined, The removal of the majority of the shed resulted in an increase in the numbers of all species taken in gill nets except the chubsuckero This increase was also noted in the total weight of each species in the not catch, The net catches just before the total kill in 1960 showed a marked increase from 105 percent to 50,6 percent in the number and 209 percent to 3105 percent in the weight, Spotted gar, chubsucker, largemouth'bass, and black crappie were the other species to show an increase in both numbers and weight, The data in Table h presents the comparison of the game and rough species in the not catch with relation to the selective shad kill of 1958, This table compares the catch in 1957, which was before the shed kill, with the catch in 1958 which was immediately after the selective treatment, The 1959 netting was done during the period when the first shad spawns were appearing while the 1960 netting reflects the effect of the increase in shad production, The total number of fish taken in gill nets is quite similar in 1957 and 1960 as in both cases the large number of shad can be considered responsible, The shad catch in 1958 and 1959 was very low since almost all of them were killed in May 1958 and apparently no spawn was obtained from the survivors until June 1959, The average weight of rough fish taken rose sharply in 1958 and lowered only slightly in 19590 This was due to the fact that the shed were not present in the catch to reduce the average, The average weight of game fish dropped from Otto pounds in 1957 to 0,37 pounds in 1958, This is believed to be due to the fact that the removal of the entire population of small shad reduced the available food and slowed the growth of game species“ This appears to be substantuated by the fact that the average weight of game species remained at 0.37 pounds in 1959, but increased to O.h8 pounds in 1960, when the shed spawns of the previous summer and fall became a part of the diet of the game specieso A comparison of the data in Table 5 with that in Table 6 discloses some facts that appear significanto Both tables contain information from net runs in the months of January and April, Table 5 presents data from 1959 and Table 6 presents data from 1960, Table 5 data was collected by 15 net sets while 22 net sets were made in the The most significant comparison is in the number of fish per 100 feet of net and the nuMber of pounds per 100 feet of net, There is little difference in the average number of fish or pounds of fish taken during the two netting periods except with regard to the shed which are not present in the 1959 netting, but are rather abundant in the 1960 sampleso If the number and weight of the shed taken, per 100 feet of gill net, in 1960 are subtracted from the total number and weight of all species taken one arrives at a figure rather close to that of the 1959 netting” CONCLUSEONS The results Obtained by following the selective shad hill of 1958 with a complete kill in 1960 indicate that the benefits from a selective kill may be very short in durationo The failure of the shed, that escaped the selective treatment, to spawn during the l958_season added about one year to the duration of the good durationo The results of the Fincastle Lake treatment indicate that the reproduc» tiwe potential of the gizzard shed is such that the removal of all the shad is the only control that can hope to last more than one or two spawning seasons in the warm water areaso The removal of the entire shad population will entail the sacrifice of a portion of the game fish crop? but it is believed that this is a justifiable expenditureo Prepared by Leonard Dr Lamb Approved by :::ta;iieriapodo«oa/1&L29’tfi::/ W . . . can" ProJect Leader Director Inland Fisheries D1Vision Date September 12 1960 Table lg n A checklist of species killed in Fincastle Lake, April 25-26, 1960; showing their relative abundance in the kill Scientific Name Lepisosteus productus Ania calva Dorosoma petenense Dorosoma cepedianum Esox americanus Ictiobus bubalus Erimxzon sucetta Cyprinus carpio Opsopoeodusm emiliae Ictalurus punctatus ggtalurus melas Iotalurus natalis Schilbeodes gzginus Fundulus notti Gambusia affinis Mieropterus salmoides Chaenobrzttus gulosus Lepomis cganellus lepomis microlophus Lepomis macrochirus kpomis humilis mpomis auritus Pomoxis annularis Pomoxis nigronaculatus Siren intermedia ambistoma tigrinun Spotted gar Bowfin Threadfin shad Gizzard shad Grass pickerel Smallmouthibuffalo Lake chubsucker European carp Pugnose minnow Channel catfish Black bullhead Yellow'bullhead Tadele madtom Starhead minnow Common mosquitofish Largemouth bass Warmouth Green sunfish Redear sunfish Bluegill sunfish Orangespotted sunfish Yellowbelly sunfish White crappie Black crappie Western dwarf siren Spotted salamander CDCD#=”aC3C>h=3>6362€13>C1C)€)H3uJCJDJCJDJC}#'CDC>ha * Note: Aeabundant, decommon, F=frequent, Osoccasional and Harare